1. Field of the Invention
The present invention relates in general to a valve operating system, and more particularly to a system for controlling an electromagnetically actuated valve of an internal combustion engine. More specifically, the present invention is concerned with a control system for controlling the electromagnetically actuated valve in such a manner as to reduce or minimize a noise inevitably produced by an electromagnetic actuator section of the valve.
2. Description of the Prior Art
For actuating intake and/or exhaust valves of an internal combustion engine, electromagnetic actuators have been hitherto proposed and put into practical use as a substitute for conventionally used cam type actuators. Due to one nature of such. electromagnetic actuators, the open/close timing of the valves is accurately and easily controlled, and thus, usage of such actuators in the engine brings about marked improvement in both engine output and fuel saving. However, due to another nature of such actuators, non-negligible noise tends to be produced under operation, which is caused by collision of an armature of the actuator against electromagnets of the same. For reducing or minimizing such noise, various attempts have been made, some of which are described in Laid-open Japanese Patent Applications 10-205314 and 10-220622. For such noise reduction, these publications propose a unique shape of the electromagnets and avoidance of collision between the armature and each of the electromagnets by producing a larger magnetic force at a certain time.
It is an object of the present invention to provide a control system for controlling an electromagnetically actuated valve, which can lower or at least minimize a noise inevitably produced in an electromagnetic actuator.
According to a first aspect of the present invention, there is provided a control system for controlling an electromagnetically actuated valve that includes an electromagnet, an armature member driven by the electromagnet and a valve driven by the armature member. The armature member and the valve are movable together to constitute a movable unit. The control system comprises a position detecting unit that detects a position of the movable unit; a speed detecting unit that detects a moving speed of the movable unit; a target speed deriving section that derives a target speed of the movable unit by processing the position of the movable unit; a comparator section that compares the speed detected by the speed detecting unit with the target speed derived by the target speed deriving section; and a control section that, in accordance with the result of the comparison by the comparator section, controls the electromagnet.
According to a second aspect of the present invention, there is provided a method for controlling an electromagnetically actuated valve including an electromagnet, an armature member driven by the electromagnet and a valve driven by said armature member. The armature member and the valve are movable together to constitute a movable unit. The method comprises detecting a position of the movable unit; detecting a moving speed of the movable unit; deriving a target speed of the movable unit by processing the position of the movable unit; comparing the detected speed with the derived target speed; and controlling the electromagnet in accordance with the result of the comparison.